The following passage is taken from Elpis Israel, 1904 edition, chapter 11 which was written by the founder of the Christadelphians, John Thomas on the topic of repentance. It is relevant because the reason many Christadelphians leave is because they find an emphasis on head rather than heart and this issue was raised by people of his day too. The critical question is whether the community has been based upon intellectual conversion rather than heart conversion.
Is this “law of faith” or correct understanding of the gospel of the kingdom (without any sorrow for sin) really repentance or is it a complex intellectual position that evades repentance? Is this what made the prayer of the sinner more acceptable than that of the Pharisee? His change of mind and disposition (without any emotions involved). Was the “piercing of the heart” of the men at Pentecost “evangelical” and unrelated to real conversion? Is accepting a set of beliefs the same as faith? You decide…
“Three things were to be preached in the name of Jesus Christ to them who believed in the promises made of God to the fathers, These were first, repentance; secondly, remission of sins; and third, eternal life (Luke 24:44-47; John 20:31). To preach the kingdom in the name of Jesus Christ was to expound the things concerning it; and to offer them to all who would become the subjects of repentance and remission of sins in his name. Neither “flesh and blood,” nor “sinners,” can inherit the kingdom of God (1 Cor. 15:50). These are fixed principles. But, why not? Because “the kingdom shall not be left to other people,” and because those, who inherit it are to possess it for ever. Now “flesh and blood” is mortal; how then can mortality inherit immortality? It is a physical impossibility. In other words, a man who only lives seventy years, cannot hold office for a thousand years; he must be made deathless before he can retain it for ever. Again, it is a moral impossibility for sinners to possess the kingdom, because the law of the kingdom is that “he that ruleth over men must be just, ruling in the fear of God.” It is the inheritance of saints, to whom the Lord will not impute sin. Two things are therefore indispensable before Jew or Gentile can inherit the kingdom -- first, a moral purification; and secondly, a physical, or corporeal, purification. The first is compassed in obeying the truth; the last, by a resurrection unto life.
Now the repentance which results from believing the gospel of the kingdom is not “sorrow for sin;” nor does it contain the least bitterness or remorse of feeling in it. The scripture word translated repentance is METANOIA, and signifies, a change of mind and purpose (Acts 5:31; 11:18). When such a change takes place from believing the truth, it is a disposition and mode of thinking such as characterized Abraham; who is the model of the faith and temper, which precedes justification in the name of the Lord. But a change of mind and purpose however “evangelical,” is only granted for repentance in the name of Jesus Christ. That is to say, though a believer of the gospel of the kingdom might possess this state of mind and child-like disposition, he would not be regarded as in repentance any more than in Jesus, until the name of Christ was named upon him according to “the law of faith.” It imports not how much a woman loves a man, she is not his wife, and therefore entitled to none of the benefits he is able to confer, until she puts on his name according to law. The name of Christ consummates everything. “Complete in him;” but out of him every thing is imperfect. Faith is unfinished, and the change of mind and disposition is incomplete, until the believer of the gospel of the kingdom puts on the name of Christ. In the act of doing this, his faith is counted to him for righteousness, or remission of sins that are past; and his change of mind and disposition is granted to him for repentance.”